1. Field
The present invention relates to the field of radio and television broadcasts and reception. More specifically, the present invention relates to a segmented broadcast signal format for traffic information and an automotive receiver adapted to selectively receive regional segments of that traffic broadcast. The present invention further provides for the conversion of selected SAP television signals to a form compatible with the input of a standard automotive radio and an integrated tuner that provides for automatic monitoring of the segmented traffic broadcast signal while otherwise providing normal radio listening.
2. Art Background
The insertion of control tones into radio and television broadcasts is well known. For example, U.S. Pat. No. 3,729,581 titled Computer Assisted Dial Access Video Retrieval for an Instructional Television System, issued to Deyrol E. Anderson, Apr. 24, 1973, describes a computer-assisted dial-access video-retrieval system. This system responds to tone commands received by telephone and broadcasts requested video information via a TV transmitter link and controls a subscriber's video tape recorder by control tones inserted into the broadcast signal. The requesting subscriber is individually addressed by a broadcast code consisting of a predetermined three variable (tone, duration, and period of silence) code. This code selectively activates the subscriber's video tape recorder, and the requested materials are then transmitted via the TV transmitter link. The transmission is followed by a reset tone which deactivates the subscriber's tape recorder.
However, systems such as this require the use of an elaborate decoders which constantly monitor audio programs to detect codes comprised of unique tone burst sequences. Such decoders must discriminate tones from random audio tones. Thus, the code sequence must be complex enough to preclude the possibility of duplication by music, speech, or any other program audio normally encountered. At the same time, the code sequence and decoder must be simple and reliable.
Early decoders used separate and distinct bandpass filters for each different frequency of interest. An improved tone sequence and decoder architecture was taught in U.S. Pat. No. 3,860,913, titled "Multifrequency Sequential Tone Decoder, issued to Weeks, Jr. and Wohnoutka, Jan. 14, 1975. This patent describes turning on and off various automated systems in response to control signaling utilizing audio tones in a broadcast medium such as a standard radio or TV audio transmission. Specifically, the patent teaches the use of active, high-Q semiconductor tunable-bandpass filters. This permits a single switchable active-filter to be responsive to different frequencies in accordance with a timed code. This is used in combination with a code that includes tones that are transmitted for a predetermined length of time, each followed by a silence of a predetermined length of time. The decoder then verifies the frequencies, the duration of each tone, a period of silence, and the duration of silence.
Another system using broadcast tone control signals is taught in U.S. Pat. No. 4,031,467, titled Alerting Process and System of Apparatus Therefor, issued to Singleton, Jr., and Whitney Jun. 21, 1977. This patent teaches a tornado warning system which includes a number of receivers pretuned to the same frequency. The receivers can be selectively activated by the use of selective triggering frequencies superimposed on the carrier frequency. Thus, only the desired receivers hear the broadcast audio message. The receivers include a timer that enables reception for a preselected time interval.
A similar addressing system is taught in U.S. Pat. No. 4,127,852, issued to Preston and Barton Nov. 28, 1978. This patent teaches a power use alarm signal broadcast over a AM or FM carrier. Remote sites are equipped with a pre-tuned AM or FM receiver which can be addressed by a fixed sequence of audio tones. The receiver turns on for a preselected period of time in response to its individual "address" of audio tones and causes lights to blink, couples an alarm message to a public address system, and automatically turns off non-essential electronic equipment.
Another addressing system is taught in U.S. Pat. No. 4,575,750, titled Communication Apparatus for use with Cable Television Systems issued to Callahan Mar. 11, 1986. This patent provides emergency audio messages on a cable carrier for users such as volunteer fireman. The transmission unit orginates messages and message class identification signals. Receivers continuously monitor the in-coming signals for a preselected trigger signal. The receiver renders the emergency messages audible when it identifies it as being authorized for that unit. A timer then enables reception for a pre-selected period of time, ar alternatively a termination signal disables reception. An override switch allows any broadcast to be rendered audible, and a manual termination switch is provided on the receiver.
These systems are addressing systems. A new type of system, which permits the selective reception of desired broadcast information is taught by U.S. Pat. No. 4,305,101, issued to Yarbrough, Stachan and Weisman Dec. 8, 1981. This patent teaches the selective reception and recording of broadcast audio/video in response to broadcast tone codes matching tone codes in a prestored list of orders. Broadcast signals are encoded with information which identifies segments to follow. The broadcast is continuously monitored for these encoded signals, which are then compared with pre-stored codes. Action is then taken in response to the received codes, such as receiving, recording or disabling recording.
However, it is desirable to provide a system of transmitting and receiving regional traffic reports that permits the decoding of traffic reports selected by a user while not requiring his listening to reports from areas of no interest to him. It is also desirable for the user to be able to listen to these reports over his automobile radio. It is further desirable to have selected traffic reports automatically switch into regular listening of the automobile radio.